1. Field of the Invention
The present invention relates to a recording sheet for ink-jet printing.
2. Description of Background Art
An ink jet printer is conventionally used for recording desired characters and images on a recording sheet, such as a paper sheet or any other medium, by directly placing ink droplets jetted from a print head. The printing speed of modern ink jet printers is ever increasing for economical reasons. Recording sheets suitable for these printers therefore need to absorb the inks very quickly. However, in the known ink jet printer, each jetted ink droplet is directly placed on the recording paper, so that a print quality or time for drying a printed image are changed according to the kind of the recording paper. That is, there is a problem in that the print quality is remarkably deteriorated when it is printed on low quality recording paper, the printed image being blurred and illegible. In order to solve such a problem, it has been proposed to use ink of a hot melt type as ink for an ink jet printer. The characteristic of these hot melt inks is that they are solid at room temperature, they are liquefied by heating for application, and they are resolidified by cooling on the printed media. Various compositions are known for a hot melt ink. Some of the known hot melt inks of the present invention contain crystalline materials. An example of a known hot melt ink comprising a crystalline fraction is disclosed in U.S. Pat. No 6,682,587. During the ink-jet process the hot melt ink is applied onto an ink-jet imaging medium (recording sheet). The recording sheet generally comprises a substrate and an ink-receptive layer formed on an imaging surface of the substrate. This substrate is then coated with specially formulated ink-receptive compositions that are capable of receiving and holding the aqueous-based inks effectively so as to generate a quality printed image. An example of a known ink-jet recording sheet is disclosed in U.S. Application Publication No. 2006/0068133. It has, however, been found that in case a crystalline fraction based hot melt is applied onto the known recording sheet, the known recording sheet will suffer from post-crystallization of the crystalline compound of the hot melt ink at the surface of the sheet. This results in a poor print quality after a few days or weeks, far shorter than the desired life expectancy. The post-crystallization process can be very fast, if the sheet surface is touched with fingers or scuffed with cotton gloves. The only known solution so far to counteract this problem is to apply a protective covering directly after printing. However, this additional step involves extra handling and costs.